A coordinated series of Golgi, connectional neuroanatomical, histochemical, biochemical and immunocytochemical experiments are proposed to study the gustatory zone of the nucleus of the solitary tract (NST) and the pontine taste area (PTA). Special emphasis is placed on the characterization of the morphological distinct classes of neurons and patterns of terminations of primary peripheral or centrifugal afferents in the NST and PTA at the light and electron microscopic levels, and their association with specific chemical markers. Ongoing work in the NST serves as the foundation for additional studies of the various functional classes of NST neurons and for embarking on new studies of the PTA. The classes of neurons within the NST and PTA are defined using quantitative morphometric procedures and electron microscopy. The efferent projections of these two brainstem nuclei are studied with the use of the anterograde transport of tritiated amino acids and autoradiography; output neurons are identified by the retrograde transport of fluorescent markers and horseradish peroxidase injections into major efferent targets of the NST or PTA. Light and electronmicroscopic immunocytochemical studies identify and localize classes of neurons in the NST and PTA, and their association with putative neurotransmitters or neuromodulators. Biochemical assays are proposed to quantify the contents of cholinergic, catecholaminergic and peptidergic substances in the NST and PTA. Collaborations are described in the areas of fluorescent microscopy, biochemistry and in the production and testing of antibodies to assorted peptides and provide opportunities to acquire different research sklls.